The difference between food poisoning and the so-called “stomach flu” is actually a bit difficult to describe, mainly because the term “stomach flu” is not really an accurate description. In both cases, the symptoms are very similar, and so are the treatments, since the condition often runs its course without medical intervention. Medical help should be sought if symptoms persist for more than 24 hours, or if they become extreme.
Food poisoning, also known as food borne illness, is caused when food becomes contaminated with something which is harmful, such as a bacteria, virus, or toxin. It can be the result of poor sanitation or improper food handling, and symptoms can emerge between two and 24 hours after eating, depending on the agent which causes the food poisoning. Headache, fever, and fatigue often emerge first, followed by nausea, vomiting, stomach cramping, and diarrhea.
The key sign that gastrointestinal distress may have been caused by food poisoning is the presence of other people who ate the same thing and also became sick. If everyone becomes ill after a family meal cooked at home, for example, food poisoning is highly likely. Food poisoning can be a bit trickier to narrow down when people eat at a restaurant, as the symptoms can take some time to emerge. For example, if people get sick two hours after dinner at a restaurant, dinner might not be the cause; it might have been the fruit everyone had at lunch.
The “stomach flu” is not actually a flu at all, since flu is caused by the influenza virus, which attacks the respiratory system. More properly, stomach flu should be known as gastroenteritis. It is caused by a viral infection of the intestines which causes irritation, and symptoms very similar to those above: nausea, vomiting, fever, diarrhea, fatigue, and chills. Gastroenteritis can be caused by consuming contaminated food, or by being exposed to a virus through poor sanitation. Food is the most common vector for gastroenteritis, so one could think of the stomach flu as a special subset of food poisoning.
In either case, the best thing for the patient is staying hydrated and resting. The symptoms will usually pass within 24 hours, although the patient may feel a bit weak for several days afterwards. Eating bland foods can also help, as can drinking products specifically designed for people with diarrhea, like pedialyte and other fortified beverages which offer nutrition in addition to hydration.
If the symptoms persist or the patient starts vomiting or excreting blood or developing an altered level of consciousness, it is time to see a doctor. The doctor can narrow down the cause and prescribe a medication to deal with the virus, bacteria, parasite, or toxin which is causing the condition. It can be helpful to know what the patient has eaten in the last 48 hours, as certain foods are more prone to contamination than others; if the patient had chicken, for example, campylobacter and salmonella would be leading suspects.